Need help on dial backup with ISP

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Apr 29th, 2010
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I've been googling around a couple hours and can't find a simple configuration for dial backup to an Internet Service Provider.

So far, what I've been able to find is direct dialing to routers and dial backup using ISDN.

All I need is for a router to dial. The ISP uses PAP/CHAP authentication and dynamically assigns IP addresses to dialup accounts.

I have an 1841 router with a T1 line on S0/0/0. I want it to fail over to the modem on the AUX port and use that as the new default gateway for all traffic.

Any help is appreciated.

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smitesh kharecha Fri, 04/30/2010 - 06:26
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Try floating route or you can also use TRACK feature...


Smitesh Kharecha

AdamPage1 Wed, 01/05/2011 - 04:10
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Hi Dan,

Did you have any joy finding a solution?

AdamPage1 Wed, 01/05/2011 - 07:37
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aha.....I've only been trying for a couple of months on and off, good to know I've still got a few months of pulling my hair out!

Bastien Migette Thu, 01/06/2011 - 01:50
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I think you can use Dial on Demand Routing (DDR) as described here:

and this particular guide as well:

Basically your dial connection will not be active until certain traffic will pass through.

Now, to pass traffic only when primary is down, you can define a static floating route as explained above, which is a route with a higher admin distance than the default one, so if the normal route is up, nothing will pass to the dialer, if it's down, the route to the dialer will be used.

To detect that primary route is down, either use dynamic routing or route tracking as suggested.

I hope that helps.




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